Field of the Invention
The invention relates to a proximity sensor with a sensor head for generating sensor signals and to a modular system for forming proximity sensors.
A proximity sensor is known, for example, from Published, Non-Prosecuted German Patent Application DE 33 18 900 A1. In the case of the known proximity sensor, a mini-transmitter that passes on the sensor signal wirelessly to another unit is already used.
It is generally known to produce proximity sensors with different outer forms, for example with a cylindrical housing of a diameter of 4, 6, 8, 12, 18 and 30 mm or else with a cuboidal housing (see in this respect, for example, ABB catalogue No. 1SAC103699L0201, printed 6/99, pages VI and VII). The outer form of the housing corresponds to the fastening openings to be provided in machine components. In the case of cylindrical housings, the housing diameter is often chosen in accordance with the sensor spacing. In this case, it is difficult, in particular in the case of very small diameters of the housing, to accommodate not only the sensor head with the sensor coil and a sensor-signal evaluation unit but also additional electronic units, such as a radio transmitter, radio receiver and antenna, within the housing.
It is accordingly an object of the invention to provide a proximity sensor which overcomes the above-mentioned disadvantages of the prior art devices and methods of this general type, which can be adapted in a simple way to differently dimensioned fastening openings.
With the foregoing and other objects in view there is provided, in accordance with the invention, a proximity sensor. The proximity sensor includes a fastening portion containing a sensor head for generating sensor signals, and an electronics portion connectable to the fastening portion. The electronics portion has a sensor-signal evaluation unit, a modulator/encoder, a radio transmitter with an antenna for emitting evaluated sensor signals and disposed downstream of the modulator/encoder, a radio receiver, a demodulator/decoder for a radio reception of sets of parameters and disposed downstream of the radio receiver, and a power supply unit. An electrical connection is provided for passing the sensor signals from the fastening portion to the electronics portion.
The advantages that can be achieved with the invention are, in particular, that the electronics portion of the proximity sensor, formed as an independent structural component, can be used universally for all variants of the fastening portions, formed as independent structural components (with different housing diameters or different housing configurations). The electronics of the proximity sensor, including the sensor-signal evaluation unit, radio transmitter, antenna and cableless power supply, does not have to be miniaturized in such a way that it also fits in fastening portions with extremely small dimensions (see, for example, proximity sensors with a cylindrical housing of 4 or 6 mm in diameter). The modular system makes it possible for proximity sensors to be produced at low cost with different fastening portions, respectively adapted to the fastening openings of machine components, it being possible in each case for the same electronics portions to be used for different fastening portions.
In accordance with an added feature of the invention, the power supply unit contains a secondary coil, a rectifier disposed downstream of the secondary coil, and a store. The secondary coil receives a medium-frequency magnetic field and performs a conversion of the medium-frequency magnetic field into electrical energy.
In accordance with an additional feature of the invention, the fastening portion has a thread suitable for engagement in a machine component.
In accordance with another feature of the invention, the electrical connection between the fastening portion and the electronics portion includes plug contacts. Alternatively, the electrical connection takes place by magnetic coupling.
In accordance with a further feature of the invention, the electrical connection includes an intermediate piece connected between the fastening portion and the electronics portion. Preferably, the intermediate piece is deformable.
In accordance with another added feature of the invention, the sensor-signal evaluation unit adaptively recognizes a connection of the sensor head for evaluating the sensor signals.
In accordance with a concomitant feature of the invention, the electrical connection between the fastening portion and the electronics portion takes place contactlessly or with electrical contacts.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a proximity sensor, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.